SA Protozoa Flashcards
Describe Neospora caninum
An apicomplexan protozoan similar to T. gondii
Neonatal paresis and abortion in cattle is characteristic of which parasite?
Neospora caninum
Outline the lifecycle of Neospora caninum.
- Dogs scavenge infected bovine tissues and ingest bradyzoite cysts
- Enteric sexual cycle
- Oocysts excreted in dog faeces. Contaminate cattle food and water.
- Asexual reproduction of tachy and bradyzoites
- Tachyzoites in cattle cross the placenta and infect the foetus
How do number of oocysts excreted by the definitive host differ between Neospora and Toxoplasma?
Toxo ++++
Neospora - only up to 500k
The dog can act as an intermediate and definitive host of N. caninum. How does this work?
Which method of transmission of N. caninum results in neonatal paresis?
How do these dogs serology compare?
- Host types
- Definitive host: ingestion of bradyzoite cysts from bovine tissues
- Intermediate host: transplacental transmission
- Transplacental transmission
- Definitive hosts are not Ab positive whereas intermeds are. Also intermeds do not have oocysts in their faeces.
What clinical signs are associated with N. caninum in puppies?
- Ataxia
- Hindlimb paresis
- Loss of reflexes
- Ascending paralysis
- Dysphagia
- Hyperextension of hindlimbs
What clinical signs are associated with N. caninum in older dogs?
- CNS disturbances
- abnormal behaviour
- vision defects
- seizures
- myocarditis
- dermatitis
- pancreatitis
Describe diagnostic techniques which can be used for N. caninum
Clinical signs - see prev slide
Serology - intermediate vs definitive hosts
CK elevation - muscle damage
Muscle biopsy - PCR or immunocytochemistry of parasites
How is N. caninum treated in dogs and cattle?
- No current approved treatment in Cattle
- Dogs: prolonged clindamycin/ potentiated sulphonamides
Remember: Prognosis is variable
Name two other minor protozoal species in dogs and describe their clinical signs.
- Isospora - diarrhoea in puppies and kittens
- Sarcocystis - abortion and meat condemnation in cattle and sheep
Traveller’s diarrhoea in humans can be caused by which protozoal species?
Giardia
Describe the morphology of Giardia trophozoites and cysts.
- T - Binucleated, tear drop shaped, 8 flagella, adhesive disc
- C - Oval/ ellipsoid, 8x12um, 2-4 nucleii
Which Giardia spp. is most relevant in the domestic species?
What is conveyed by the spp. strain assemblages? Which assemblages are associated with multi-host infection?
Giardia duodenalis
Assemblages of G. duodenalis convey species specific infectivity.
- A - Human, livestock, dog, cat
- B - Human, dog, rat
Outline the lifecycle of Giardia.
- Infective cysts are ingested by the host
- Encyst in the small intestine and develop to trophozoites
- Trophozoites multiply asexually by binary fission (longitudinal)
- Fate
- Single trophozoites excreted disintegrate
- Multinucleated resistant cysts excreted in the faeces
What clinical signs are associated with Giardia infection?
How can infection be diagnosed?
- Trophozoites erode mucosa and villi
- Malabsorptive diarrhoea
- Steatorrhoea (greasy stools)
Diagnosis is via identification of trophozoites and cysts in stools.